Flour products made from flour obtained by grinding cereals such as wheat, barley, oat, rice, glutinous rice, etc. are used as daily staple food by an overwhelming majority of the people around the world. These flour products mostly have white color. People usually relate bright color with the quality and freshness of the flour product. However, the appearance of a flour product may be affected badly during storage and handling due to enzyme browning or non-enzyme browning such as Maillard reaction and the like which darken the color of the flour product. To solve this problem, a chemically synthesized oxidant is generally added into the flour product for whitening. Benzoyl peroxide is one of such chemically synthesized oxidants, which whitens flour by oxidizing carotenoid in the flour that makes the flour slightly yellow, and had been widely used as an effective flour whitener for a long time. Nevertheless, it has been discovered that benzoyl peroxide has some risk of carcinogenesis. In addition, it may add to hepatic burden, leading to pathological change of liver and kidney, as well as various diseases such as atherosclerosis. As such, the Ministry of Health of PRC issued a pronunciamento that forbade production of benzoyl peroxide and calcium peroxide as food additives and addition thereof into flour, and banned food additive plants from manufacturing and selling benzoyl peroxide as a food additive. Therefore, it is desirable to obtain an alternative whitener which has good whitening effect without any toxic side-effect.
Saccharide alcohol is a polyol having two or more hydroxyl groups. In contrast to petrochemically synthesized polyols such as ethylene glycol, propylene glycol, pentaerythritol and the like, the saccharide alcohol is derived from an annually renewable saccharide in nature as raw material. Hence, it is inexhaustible and inexpensive. A saccharide alcohol is formed by reducing the aldehyde or ketone group on a saccharide molecule into hydroxyl group. For example, glucose may be reduced to sorbitol; xylose to xylitol; maltose to maltitol, fructose to mannitol, etc. Although saccharide alcohols are not saccharides, they exhibit some attributes of saccharides because they are mostly prepared by reducing saccharides via hydrogenation. Saccharide alcohols are safe foods with no limited edible amount as approved by both CAC and JECFA, two international food and health organizations. Since saccharide alcohols do not decay teeth or increase blood sugar, and provide certain calories for diabetes patients, they may be used widely in place of sugars as nutrient sweeteners in sugar free foods. Saccharide alcohols under worldwide mass production currently include sorbitol, maltitol, xylitol, erythritol, mannitol, lactitol, isomaltitol, etc., among which erythritol is an important representative. Erythritol, also named erythrose alcohol and bearing the structure shown by formula (1), is a polyol sweetener. It exists naturally in algae, mushrooms, melons, grapes and fermented foods, and is also found in human eye balls and blood serum. It is quite suitable for use as a substitute sweetener for diabetes patients, because it cannot be degraded by enzyme after ingested; instead, it can only be transferred from blood through kidney to urea from which it is discharged, and it does not take part in sugar metabolism or contribute to the variation of blood sugar. Additionally, erythritol will not ferment in colon, and thus will not cause gastro-intestinal discomfort. Moreover, as a low calorie sweetener, it will not decay teeth. Owing to the above advantages, erythritol is widely used in various foods.

Erythritol may undergo polymerization to produce polyerythriol. The polyerythritol is a golden sticky liquid which has excellent low temperature softness, high stability under acidic, alkaline and high temperature conditions, low volatility, and high adhesive ability.
Hee-Jung, et al. (Appl Microbiol Biotechnol, 2010, vol. 86: pp. 1017-1025) and B. Tong et al. (Journal of Thermal Analysis and calorimetry, 2009, vol. 95: pp. 469-475) have studied the production, properties, thermodynamic behaviors and application of erythritol. It is mentioned in Patent Application US2003/0017132 that erythritol polymers and aliphatic acid esters or aliphatic ethers thereof may be used as surfactants, emulsifiers, cosmetic raw materials, detergents, defoamers, dispersants, solubilizers, preservatives, etc. Their combinations or raw materials are also mentioned. However, the use of a polysaccharide alcohol as a whitener in a flour product has not been disclosed up to date. Particularly, there is no mention of polyerythritol for such use.